The Gauntlet Rotary Magazine advances each pellet with the operation of the bolt on the Umarex Gauntlet PCP air rifle. This magazine is a .177 caliber and holds 10 airgun pellets. The magazine slides into the receiver with ease. Loads easily. And has numbers on it to indicate the shot you are on so that you're fully aware how many rounds you have left before the magazine is empty. 2 magazines included in this package.